Fining agents are substances commonly used in liquid foodstuff or beverage production for clarification, stability, and improvement of sensory characteristics. These agents help provide clarity, avoid the formation of amorphous precipitates (e.g. macromolecules such as protein, sugars, tannins) and crystals (e.g. potassium or calcium tartrates), and are used to make corrections to the color and flavor of the products treated.
Some of the clarifying agents most typically used in beverage production include substances such as bentonite, protein-based materials such as gelatin, casein, and albumin, activated carbon, and synthetic products like polyvinylpolypyrrolidone (PVPP).
PVPP is a clarifying agent produced by the polymerization N-vinyl-2-pyrrolidone in alkaline media. For example, in white wine production PVPP is used to remove the brown color formed by effect of enzymatic or chemical oxidation, as well as to prevent the formation of pink color due to an unknown reaction that has been linked to unstable phenolic intermediates. PVPP is a synthetic product capable of non-selective adsorption of the undesired substances, mainly oxidizable phenolic compounds. Depending on the application and market restriction, PVPP additions can range between 0.1 to 0.8 g/L.
Due to their limited selectivity, some of the negative consequences of the use of fining agents are related to their capacity to remove compounds which are responsible for some of the organoleptic features of the product (e.g. aromas), thus reducing the quality of the products.
In this document, the description of the scope of the invention is usually exemplified by references to the wine industry, nevertheless, this must not be understood as a limitation of the invention to said industry, since the compounds, compositions and methods of the present invention can be applied to a wide variety of liquid foodstuffs or beverages. Therefore, the terms liquid foodstuff or beverage must be understood in their widest meaning, such as for example, but not limited to, fruit juices, plant juices or extracts, fermented beverages, alcoholic fermented beverages, such as wine, beer, cider, sparkling wine, ale, rye beer, chicha, sake, pulque; or distilled alcoholic beverages such as whisky, whiskey, vodka, korn, brandy, cognac, vermouth, pisco, armagnac, branntwein, singani, arak, ouzo, pastis, sambuca, grappa, orujo, aguardiente, ron, cachaça, tequila, mezcal, among many other liquid foodstuffs or beverages containing phenolic compounds which, depending on the requirements of the industry or the customer, should be removed from the liquid foodstuff or beverage.
For a long time the scientific and technical progress in the wine industry has been centered mostly on efforts to stabilize wine and thus avoid the precipitates. The existence of precipitates reflects in the quality and standard of the wine. Indeed, it is well-known that customers finding precipitates usually return a wine product to the manufacturer.
In general, the existence of deposits of crystals and/or colorant matter in the wines is not acceptable regardless of the age of the wine; the demand is for clarity. Hence, clarification and stabilization of wines are performed to avoid any defects in clarity or any physical-chemical or microbiological disequilibrium.
Clarification is usually facilitated by the use of mineral products, such as bentonite, organic products, such as gelatin and egg whites and blood albumins, and also synthetic materials, such as polyvinylpolypyrrolidone (PVPP), a product specifically developed to this end.
Silicate suspensions and enological tannins also take part in the clarification, although they are not considered as clarifying agents in their own right but as aids to the process, especially when performed with mineral or organic products.
Other substances, such as charcoal, have reduced clarifying power but give a better color, thus improving the appearance of the product.
Filtration is also considered to be a stabilization operation because it eliminates those substances and microbial agents that are responsible for precipitates. The most common method of performing filtration is through the use of nylon filters or other materials with a specific pore size.
The main disadvantage of using PVPP and the other agents is their poor selectivity. There is a chance to eliminate the vital compounds from the product, which will affect its quality. Furthermore, PVPP works optimally at a defined pH range.
A new area being developed is that of smart polymers that have many advantages and applications. Particularly, these smart polymers can be used to trap phenolic compounds with high selectivity according to the requirements of a particular industry. Other advantages that these polymers have is their easy synthesis and characterization in addition to being environmentally and biologically benign, easy to separate from the final product and a selectivity that can be altered by changing the functional group of the polymers.
One way to address the above problems is through the detection, quantification and removal of unwanted substances using smart polymers. The use of branched polymers as opposed to the traditional linear ones, on the removal of unwanted substances, could largely improve the efficiency and specificity of practices where traditional methods are employed.
The procedure employed for the development of these smart polymers consisted on the following: The identification of target polyphenols common to most fruit-based beverages, the synthesis and chemical characterization of an array of smart polymers based on their potential binding capabilities against phenolic compounds, the screening of the interaction between the polymers and selected phenolic compounds via liquid chromatography and UV-Vis spectrometry, and testing of the polymers in real food matrices (e.g. wine).
Thus, the problem to be solved by the present invention is removing selectively unwanted compounds from a liquid foodstuff or beverage, with a high yield, and a broad working pH range, and the solution proposed in the present invention is providing compounds or compositions for selective adsorption of compounds which affect negatively the quality of a liquid foodstuff or beverage.
The present invention is directed to compounds which have shown that adsorb selectively specific phenolic compounds which are responsible for crystallization in beverages, or produce haze.
In order to solve the proposed technical problem, different polymers were designed, tested, and screened which would have the higher selectivity and yield for a set of identified specific compounds. These polymers resulted to be specific forms of polyaniline, and polyamidoamine polymers functionalized with polyaniline polymers.
Polyaniline is a conducting polymer formed by combination of aniline monomers. The polymerized aniline monomers can be found in different oxidation states, where the fully reduced state is known as leucoemeraldine, while the fully oxidized state is known as (per)nigraniline. The intermediate state, emeraldine, has two forms, one the emeraldine base (PANI-EB) is the neutral form, and emeraldine salt PANI-ES) is the protonated form. The use of polyaniline polymers has been primarily directed to semiconductive devices, or electric devices; its use in batteries or in the conversion of chemical energy to electrical energy, whereas the application of polyaniline polymers in the food industry has been limited to the use of the compound as a sensor, for example for evaluating the toxicity of a food product.
Other part of the molecules considered in the present invention are dendrimers. The dendrimers correspond to a repetitively branched molecule based on polymers. A dendrimer is usually symmetric around its core and might adopt a spherical shape. There are high and low molecular weight dendrimers, depending on the amount and length of branches. These molecules are typically used as a core for a larger molecule which would have specific features and functions depending on the functional groups that can be added to the surface of a dendrimer.
Dendrimers can also be classified in terms of its generation. The generation corresponds to the number of repeated branching cycles that are performed during its synthesis. The higher the generation of a dendrimer, the higher the number of exposed functional groups in its surface.
In particular, the present invention is directed to polyamidoamine (PAMAM) dendrimers. The core of PAMAM is a diamine (commonly ethylenediamine), which is reacted with methyl acrylate, and then another ethylenediamine to make the generation-0 (G-0) PAMAM. Further cycles of reactions will then render higher PAMAM generations.
The use of PAMAM dendrimers has seen a wide variety of applications. For example, PAMAM polymers have been used in pharmaceutical compositions as carriers, as substrate for analyses or detection of compounds, associated with nucleic acids for therapeutic purposes,